What is the solution for a fixed string oscillating at both ends?

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    Oscillation String
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Homework Help Overview

The discussion revolves around a fixed string oscillating at both ends, described by a partial differential equation. The original poster presents the problem of finding the displacement of the string over time given specific initial conditions.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the method of separation of variables as a potential approach to solve the problem. There is a focus on rearranging the equation and defining variables to facilitate separation.

Discussion Status

The conversation is ongoing, with participants exploring the implications of the separation of variables method and its application to the problem. There is no explicit consensus yet, but a line of reasoning is being developed regarding generic solutions to the partial differential equation.

Contextual Notes

The original poster notes that this is not a traditional homework problem, which may influence the nature of the discussion and the expectations of responses.

saturnsalien
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This isn't actually a homework or coursework problem, but the style of the question is similar so I'm posting it here. Anyways, here goes. Consider a string of length L clamped at both ends, with one end at x=0 and the other at x=L. The displacement of the oscillating string can be described by the following equation:
\frac{\partial^2 \Psi}{\partial t^2}=\frac{\partial^2 \psi}{\partial x^2}

<br /> \textrm{Given that at t=0:}\\<br /> \&gt;\&gt;\&gt;\&gt; \psi(x,0)=\frac{2xh}{L},0\leq x\leq \frac{L}{2}\\<br /> \&gt;\&gt;\&gt;\&gt; \psi(x,0)=\frac{2xh}{L},(L-x),\frac{L}{2}\leq x\leq L\\<br /> \textrm{Show:}\\<br /> \&gt;\&gt;\&gt;\&gt; \psi(x,t)=\sum_{m=1}^\infty\sin\left(\frac{m\pi x}{L}\right)\cdot\cos\omega_mt\cdot\left(\frac{8h}{\pi^2m^2}\right)\cdot\sin\left(\frac{\pi m}{2}\right)<br />

So, how do we go about doing that?
 
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Do you know the method of separation of variables?
 
haruspex said:
Do you know the method of separation of variables?

Yeah, that's just rearranging the equation so that different variables occur on opposite sides of the equation. You can also do this by defining a variable as some expression, substitute, and the separate them.
 
So what does that give you for generic solutions of the PDE?
 

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